The present invention relates to machines for coating granular articles, such as pharmaceutical or confectionery products, with an outer layer.
Currently, articles to be treated are coated in machines equipped with a rotating drum, called coating pan, inside which they are put.
The coating pan is connected with perforated hollow bodies, which extend from a manifold whose axis is parallel to the rotating drum axis and which are immersed in the moving mass of articles to be treated.
A suitable liquid mixture is sprayed on the articles through nozzles, so as to form a protective coating.
Afterwards, a flow of hot air is sent into the articles mass, so as to dry the coating layer.
According to a known solution, the ventilation air is freely introduced into the coating pan by a pipe connected to the rear part thereof and later it is aspirated by the above mentioned perforated hollow bodies immersed in the mass of articles.
According to another use of the above mentioned machine, the neutral granules are coated with mixtures of active principles and excipients, so as to form e.g. controlled release medicine pellets.
In this case, a predetermined quantity of neutral granules are introduced into the coating pan, so as to be covered, with help of a suitable binder, with layers of mixed powders containing active principles and excipients.
The ventilation air is introduced through the above mentioned perforated hollow bodies and sucked by a pipe connected to the rear part of the coating pan.
One of disadvantages of the known machines derives from the fact that the ventilation of the articles by the perforated hollow bodies is not always performed at the best.
The object of the present invention is to propose a machine for coating granular articles, which allows to optimize the penetration of perforated hollow bodies into the moving mass of the articles to be treated.
Another object of the present invention is to propose a very versatile machine, which can be used either for coating pharmaceutical or confectionery products with an outer protective layer, or coating the neutral granules with mixtures of active principles and excipients to obtain e.g. pharmaceutical pellets.
The above mentioned objects are obtained, in accordance with the claims, by a machine for coating granular articles and the like, including:
a rotating drum or coating pan rotating around a rotational axis and containing a predetermined mass of articles to be treated;
a tubular manifold having axis parallel to the rotational axis of said coating pan and set in communication with an outer first pipe;
a plurality of perforated hollow bodies, extending from said manifold and dipped into the moving mass of said articles being treated;
a second pipe connected to said coating pan to create a flow of air for ventilating said articles.
According to a first embodiment, the perforated hollow bodies are telescopic, so as to allow adjustment of their length in order to change the depth of penetration in the moving mass of said articles inside the coating pan.
According to a second embodiment, the perforated hollow bodies have a distal part inclined with respect to a vertical axis of said hollow body and whose cross-section is oblong with pointed ends.
According to a third embodiment, the first pipe and second pipe are aimed at being connected, by a commutation member, alternately to a tube introducing air for drying treated articles and to a discharge tube.